1. Field of the Invention
The present invention relates to a drainage structure that is capable of draining a liquid such as water that has intruded into an apparatus to the outside. The present invention also relates to an information processing unit including such a drainage structure.
2. Description of Related Art
In recent years, many notebook PCs are provided with waterproof, drip-proof functionality on the assumption that drinks and the like may be spilled on notebook PCs or raindrops and the like may adhere to notebook PCs during outdoor use. As an example of the waterproof, drip-proof functionality, a drain for draining a liquid that has intruded from an upper face of a personal computer to a bottom face side of the personal computer is provided so as to prevent accumulation of the liquid inside the personal computer.
JP 7-234749A discloses a keyboard in which, as a waterproofing mechanism, a surface for guiding a water droplet to an insertion port leading to a back face of a switch panel through a molded hole is provided on the surface of the switch panel. JP 7-234749A discloses a keyboard in which a draining pipe having a sufficient length to pass through a switch unit and a support panel and surrounding the molded hole is formed on the back face of the switch panel by integral molding during the forming of the switch panel.
JP 2003-122454A discloses a notebook PC having a keyboard assembly that is configured to include a base plate, a plurality of key buttons mounted on the base plate, and a drainage means for draining a liquid that has permeated between the key buttons.
JP 2007-249624A discloses a draining structure of a notebook PC equipped with, in the main body thereof, a disk drive to which a disk-shaped recording medium can be removably attached, the draining structure including a disk cover that covers the disk drive and grooves that are provided in positions corresponding to both sides of the disk cover in a lower housing of the notebook PC. The draining structure can discharge efficiently a liquid, that causes electrical failure, even when the liquid intrudes from the top of the disk drive.
However, in the case where there is no sufficient drainage region between the housing and an installation surface (table top surface), liquid that has drained to the bottom face side through the above-described drain does not flow out from the drainage grooves to the outside due to surface tension, but rather remains at that position. For this reason, there are the following restrictions: for example, it is necessary to secure a wide space in the vicinity of the drain by increasing the height of rubber feet or the like disposed on the back face of the housing in order to provide sufficient clearance between the back face and the installation surface, or it is necessary to dispose the drain in an area where sufficient space can be secured.
Moreover, assuming a notebook PC has a disk drive in the upper face of the housing where a keyboard and the like are disposed, if a user spills a liquid on the upper face, in some cases, the liquid intrudes into the disk drive through a gap between a lid for opening and closing the disk drive and the upper face of the housing. In order to drain liquid that has intruded into the disk drive to the outside, a configuration in which a drainage groove is formed inside the disk drive along an edge thereof can be conceived. However, in the case where a drainage groove is provided, it is necessary to let the liquid accumulated in the drainage groove flow to the outside of the housing, which makes it necessary to form the drainage groove so as to extend to a front face of the housing and to form the lid into a shape that covers up to the front face of the housing.